Objectives. Co-occurrence of alcohol use disorder (AD) and posttraumatic stress disorder (PTSD) is common. Research supports exposure therapy as the front line treatment for PTSD as this approach is most likely to lead to sustained recovery from the disorder. However, individuals with AD are generally not offered exposure therapies because of beliefs that exposure would lead to engagement in greater alcohol use and other dangerous behaviors. Most research and clinical treatment for AD/PTSD have involved coping skills based therapies that have generally not shown sustained reductions in alcohol use and PTSD symptoms. A growing body of evidence suggests these individuals with AD/PTSD are able to handle and benefit from exposure. This proposed trial will compare an integrated exposure psychotherapy to an integrated coping skills psychotherapy for the treatment of AD/PTSD. In addition, mechanisms of change for Veterans with AD/PTSD in both treatment conditions, including therapy process variables, changes in negative affect, and sleep problems, will be explored. Significance: This project addresses a critical barrier in the field - the widely held belief that individuals with AD and PTSD cannot tolerate exposure therapy, although it is the best practice treatment for PTSD. If completed, this project will help change the practices that drive treatment for this highly prevalent and highly distressed population. The fundamental rationale is to improve the evidence base that informs how patients with AD/PTSD can attain sustained recovery. Innovation: This application seeks to shift current clinical practice paradigms. A refinement to existing interventions is proposed through integration of two evidence based treatments. The simplicity of the exposure therapy protocol makes it amenable to dissemination and modification to AD treatment settings. Methodology. We propose a randomized controlled trial to evaluate an integrated exposure-based treatment (Integrated Prolonged Exposure; I-PE) for concurrent AD and PTSD that is evidence based and includes both in-vivo exposure and trauma processing. The primary aim will be to conduct a randomized controlled trial to evaluate the effects of I-PE when compared to a present-focused coping skills based intervention (Seeking Safety) in 148 male and female Veterans who have AD and PTSD. The hypotheses are that at post-treatment both groups will show reductions in alcohol use, but I-PE will demonstrate greater reductions in PTSD symptoms than SS. At 5- and 8- month post-baseline follow-up, I-PE will have significantly fewer percent drinking days and fewer PTSD symptoms than SS. In addition, mechanisms of change in both treatment conditions will be examined.